The present invention relates to synchronous time systems and particularly to systems having “slave” devices synchronized by signals transmitted by a controlling “master” device. More particularly, the present invention relates to synchronous time systems, wherein the master device wirelessly transmits the signals to the slave devices.
Conventional hard-wired synchronous time systems (for example clock or bell systems, etc.) are typically used in schools and industrial facilities. The devices in these systems are wired together to create a synchronized system. Because of the extensive wiring required in such systems, installation and maintenance costs may be high.
Conventional wireless synchronous time systems are not hard-wired, but instead rely on wireless communication among devices to synchronize the system. For example, one such system utilizes a government WWVB radio time signal to synchronize a system of clocks. This type of radio controlled clock system typically includes a master unit that broadcasts a government WWVB radio time signal and a plurality of slave clocks that receive the time signal. To properly synchronize, the slave clock units must be positioned in locations where they can adequately receive the broadcast WWVB signal. Interference generated by power supplies, computer monitors, and other electronic equipment may interfere with the reception of the signal. Additionally, the antenna of a radio controlled slave clock can be de-tuned if it is placed near certain metal objects, including conduit, wires, brackets, and bolts, etc., which may be hidden a building's walls. Wireless synchronous time systems that provide reliable synchronization and avoid high installation and maintenance costs would be welcomed by users of such systems.
According to the present invention, a wireless synchronous time system comprises a primary event device or “master” device including a first receiver operable to receive a global positioning system (“GPS”) time signal, and a first processor coupled to the first receiver to process the GPS time signal. The primary event device also includes a memory coupled to the first processor and operable to store a programmed instruction, including a preprogrammed time element and a preprogrammed function element. The primary event device also includes an internal clock coupled to the first processor to store the time component and to increment relative to the stored time component thereafter to produce a first internal time. A transmitter is also included in the primary event device and is coupled to the first processor to transmit the first internal time and the programmed instruction.
The synchronized event system further includes a secondary event device or “slave” device having a second receiver to wirelessly receive the first internal time and the programmed instruction, which are transmitted by the primary event device. The secondary event device includes a second processor coupled to the second receiver to selectively register the programmed instruction, a second internal clock coupled to the processor to store the time component and to increment relative to the stored time component thereafter to produce a second internal time, and an event switch operable to execute the registered programmed instruction when the second internal time matches the preprogrammed time element of the programmed instruction.
In preferred embodiments, the secondary event device or “slave” device may include an analog clock, a digital clock, a time-controlled switching device (e.g., a bell, a light, etc.), or any other device for which the time and functionality need to be synchronized with other devices. In these devices, the programmed instruction includes an instruction to display time and/or an instruction to execute a predetermined timed function. The programmed instruction is broadcast to the “slave” unit devices by the primary event device or “master” device. In this way, for example, the master device synchronizes the time displayed by a system of analog slave clocks, synchronously sounds a system of slave bells, synchronizes the time displayed by a system of slave digital clocks, or synchronizes any other system of devices for which a time and/or functionality are desired to be synchronized.
In preferred embodiments, these systems further include a power interrupt module coupled to the processors to retain the internal time and the programmed instruction in the event of a power failure. Both the “master” primary event device and the “slave” secondary event device are able to detect a power failure and store current time information into separate memory modules.
The system is synchronized by first receiving a GPS time signal at the master device and setting a first internal clock to the GPS time signal. The first internal clock is then incremented relative to the GPS time signal to produce a first internal time. Operational data in the form of the programmed instruction, including the preprogrammed time element and the preprogrammed function element, is then retrieved from a memory and is wirelessly transmitted along with the first internal time. A second receiver at the “slave” device wirelessly receives the first internal time and the operational data and selectively registers it. A second internal clock within the “slave” device is set to the first internal time and is incremented relative thereto to produce a second internal time. In preferred embodiments, such as an analog clock, the second internal time is simply displayed. In other slave devices, such as a system of bells, a function is identified from the preprogrammed function element and is executed (for example, the bells are rung) when the second internal time matches the preprogrammed time element.
Additional features and advantages will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.